Photos of the bomb remnants

The remains of a black backpack that the FBI says contained one of the bombs that exploded during the Boston Marathon.
AP Photo/FBI

Photos of the bomb remnants

This image from the Federal Bureau of Investigation and Department of Homeland Security shows the remains of a pressure cooker that the FBI says was part of one of the bombs that exploded during the Boston Marathon.

AP Photo/FBI
| April 17, 2013

Boston Marathon bomb scene pictures taken by investigators show the remains of an explosive device.

Reuters
| April 17, 2013

The remains of a black backpack that the FBI says contained one of the bombs that exploded during the Boston Marathon.

AP Photo/FBI
| April 17, 2013

Many questions remain about the chemical makeup of the explosives within the bomb and exactly how they were triggered, but on Tuesday investigators announced some progress.

Reuters
| April 17, 2013

Boston Marathon bomb scene pictures taken by investigators show the remains of an explosive device.

Reuters
| April 17, 2013

Investigators recovered parts of the bombs, enabling them to determine they were constructed out of two 6-liter pressure cookers packed with nails, metal, and ball bearings.

Reuters
| April 17, 2013

Debris from the explosion was found on rooftops, giving a sense of the bomb's force.

Reuters
| April 17, 2013

By looking at damage to a structure or the types of injuries, it is possible to reconstruct aspects of the device.

Reuters
| April 17, 2013

Investigators are working with fragments painstakingly gathered at what is considered the city’s largest-ever crime scene.

Reuters
| April 17, 2013

The FBI asked the public for tips on anyone who may have been lugging a heavy black bag near the finish line.

Reuters
| April 17, 2013

The bomb-making technique used in the attack was detailed in a 2010 article in the online magazine, Inspire, published by the terrorist group Al Qaeda.

Reuters
| April 17, 2013

A pressure cooker bomb “is not a high-tech device,” said Michael White, director of explo­sives and training with MSA Security.